Characterization of polyethylene glycol hydrogels for biomedical applications

Abstract

Polyethylene glycol is one of the most widely used synthetic materials for biomedical applications. Its biocompatibility, flexibility, and 'stealth' properties make it ideal for use in drug delivery applications. The main objective of this paper is to characterize the structural and mass transfer properties of polyethylene glycol hydrogels for applications in drug delivery and biological immobilization. Swelling behavior of the gels was studied to determine the mesh size, and other significant structural parameters of the gel. For accurate design of drug delivery device, along with network design, mathematical modeling of release profiles was performed. The study of PEG hydrogels was done in two distinct phases. The first stage consisted of analyzing diffusion properties of homogenous PEG hydrogels with varying molecular weights (MW 200, 400, 8000, 10000, 14000, 20000). The release of fluorescein dye from each gel was analyzed, and it was observed that diffusive properties of PEG gels vary drastically with molecular weight. The lower molecular weight PEGs had lower diffusion coefficients, but their Fickian release profile was easy to analyze and predict. The higher molecular weight PEGs, on the other hand had large diffusion coefficients, but with anomalous release profiles that were difficult to analyze analytically. This led to the investigation of combination gels, or binary mixtures of two different molecular weight PEGs. These gels were found to have intermediate properties, in accordance with the mass fractions of its constitutive PEGs. This linear relationship allowed for development of a hybrid gel with required diffusive properties, and a predictable mechanism of analyte release.